10/20 Recording System

skull-landmarks-10-20-system

4 major landmarks

  • The Nasion – the indentation on the bridge of the nose between the eyes
  • The Inion – the midline bump on the inferior occipital bone near the junction of the cranium and spine
  • 2 peri-auricular notches – notches near the tragus of the anterior ear

3 fundamental lines that all other 10/20 sites are derived from:

  • 10% line – the circle line measured around the head 10% up from each of the 4 landmarks
  • C line – the line measured from the L and R peri-auricular notches
  • Z line – the line measured from the nasion to inion

frontal 1020

Frontal view

  • Shows the 10% measured from L and R peri-auricular notches.
  • Shows the C-line formed by the coronal plane

lateral 1020

Lateral view

  • Shows the 10% measurement from the nasion and inion
  • Shows the Z line formed int he saggital plane

superior 1020

Superior view

  • An axial view of the 3 fundamental lines and electrode sites of the 10/20 system

Detailed measuring of the 10/20 system is a very important component of accurate EEG recordings.  When electrodes are properly placed according to the 10/20 system, the coverage of the hemisphere is symmetrical.  If the electrodes are not symmetrically placed asymmetries may occur during recording.

Brain AreaL hemisphereMidlineR hemisphere
Frontal PoleFp1FP2
Frontal F3F4
Inferior FrontalF7F8
Mid-frontalFz
Anterior TemporalT1T2
Mid-temporalT3T4
Posterior TemporalT5T6
CentralC3C4
Vertex or Mid-centralCz
ParietalP3P4
Mid-parietalPz
OccipitalO1O2
CerebellarCb1Cb2
Non Scalp Leads
AuricularA1A2
NasopharyngealPg1Pg2

 

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